1. Field of the Invention
The present invention relates to a novel protein, and a DNA coding said protein, as well as to the preparation of said protein.
2. Description of the Prior Art
Nowadays, the treatment of cancers is mainly attained by surgical operations, chemotherapies and radiotherapies. Although most of cancers may be cured by such a treatment, a part of viable cancer cells remaining after such a treatment may be scattered throughout the body of a cancer patient, and may cause a more serious cancer-metastasis and even shorten the patient's life span. If the metastasis of cancers can be inhibited, cancer patients's pain would be relieved, and their life spans would be extended much more. Therefore, the development of agents which effectively inhibit the metastasis of cancers has been in a great demand. In general, the metastasis of cancers, however, has been considered to occur via a complicated process, and this hinders the realization of satisfiable cancer metastasis-inhibitory agents.
Although a variety of proteins possessing cancer metastasis-inhibitory activity were reported, the present protein absolutely differs from them. Examples of such a conventional protein are interferons and interleukin 2 which have been reported to have cancer metastasis-inhibitory activity. The present protein clearly differs from such a conventional protein in molecular weight and amino acid sequence. None of conventional proteins have not yet been realized as a cancer metastasis-inhibitory agent. In Japanese Patent Laid-Open No. 308,799/90, a cancer metastasis-inhibitory factor produced by cells derived from human hematopoietic tissues is reported and its structure and physicochemical properties are, however, far from substantial elucidation because the description in the patent is vague and it only teaches the molecular weight ranging 10,000-450,000.